I propose to continue my work in the area of mammalian proline metabolism with these objectives: (1) to define the biochemical steps in the biosynthesis of proline from glutamate; (2) to elucidate the pathophysiology of several genetic defects in proline metabolism; (3) to define regulatory mechanisms which coordinate proline metabolism with the metabolism of ornithine, arginine and collagen. To approach these objectives I will assay the activity of the enzymes of proline metabolism as well as measure the concentration of several key substances. My studies will take advantage of currently available and newly isolated mutant mammalian cell lines with defects of proline biosynthesis and degradation, and two mouse strains deficient in proline oxidase and ornithine carbamoyltransferase. Regulation of proline and collagen metabolism will be examined by determining the effects of perturbations of collagen biosynthesis on the proline biosynthetic and degradative enzymes of chondrocytes.